.m-header{
    position: fixed;
    top:0;
    left:0;
    height:56px;
    width:100%;
    text-align: center;
    line-height: 56px;
    background-color: #000;
    color:#FFF;
    font-size:18px;
    i{
      position: absolute;
      left:10px;
    }
  }